EP1189852B1 - Boron carbide cast bodies - Google Patents
Boron carbide cast bodies Download PDFInfo
- Publication number
- EP1189852B1 EP1189852B1 EP00927513A EP00927513A EP1189852B1 EP 1189852 B1 EP1189852 B1 EP 1189852B1 EP 00927513 A EP00927513 A EP 00927513A EP 00927513 A EP00927513 A EP 00927513A EP 1189852 B1 EP1189852 B1 EP 1189852B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- boron carbide
- making
- cast body
- body according
- mixture
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C33/00—Moulds or cores; Details thereof or accessories therefor
- B29C33/56—Coatings, e.g. enameled or galvanised; Releasing, lubricating or separating agents
- B29C33/565—Consisting of shell-like structures supported by backing material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
- B29C39/02—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of definite length, i.e. discrete articles
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
- C04B35/56—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides
- C04B35/563—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides based on boron carbide
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C2791/00—Shaping characteristics in general
- B29C2791/004—Shaping under special conditions
- B29C2791/006—Using vacuum
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C33/00—Moulds or cores; Details thereof or accessories therefor
- B29C33/38—Moulds or cores; Details thereof or accessories therefor characterised by the material or the manufacturing process
- B29C33/3814—Porous moulds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2707/00—Use of elements other than metals for preformed parts, e.g. for inserts
- B29K2707/02—Boron
Definitions
- This invention relates to the making of boron carbide cast bodies suitable for sintering.
- Boron carbide is an extremely hard substance, with a hardness exceeded only by diamond and cubic boron nitride. However, it has hitherto proved difficult to utilise the full potential of the material as a result of the difficulties met in manufacturing shaped articles.
- An essential step in the production of articles is the formation of the cast body (or green body).
- a method of making a boron carbide cast body suitable for sintering including the successive steps of mixing boron carbide particles with an aqueous binder system to form a homogenised slurry mixture; casting the mixture into the required shape; and drying the mixture, wherein the boron carbide particles have a median particle size in the range 1.5 to 3.5 ⁇ m.
- This method ensures excellent reproduction of cast detail without using potentially harmful organic liquids. There is no requirement to granulate the powder/binder mixture and there is no need to subject the system to high pressures, however, that method of manufacture remains an option because the aqueous slurries produced can be granulated by spray drying or freeze drying.
- the specific area of the boron carbide particles is preferably greater than 7 m 2 /g and typically in the range of 7 m 2 /g to 12 m 2 /g. This produces a relatively high density body after sintering.
- the boron carbide particles have a median particle size in the range 1.5 to 3.5 ⁇ m. Preferably at least 95% of the mass is less than 12.7 ⁇ m. Use of such small particles enables achievement of a high density sintered body.
- the boron:carbon atomic ratio is preferably between 3.7:1 and 4.4:1 in order that the boron carbide in the cast body can be sintered to a high density.
- the boron carbide is preferably more than 99.3% pure excluding boron oxide and boron nitride, or more than 97% pure including boron oxide and boron nitride.
- the binder system comprises a binder and a plasticiser.
- the plasticiser is chosen to increase the strength of the cast body so that it is less likely to suffer damage prior to sintering.
- the binder causes the boron carbide particles to aggregate in a satisfactory manner and adds carbon to the body during the sintering process.
- the plasticiser is preferably chosen from one or more of glycerol, a low molecular weight polyethylene glycol and a low molecular weight polypropylene glycol. These compounds are cheap, readily-available and of low toxicity.
- the binder system includes a dispersant.
- the dispersant ensures that the boron carbide particles do not form large aggregates which would not remain satisfactorily in suspension.
- the dispersant is preferably chosen from one or more of a water-soluble copolymer based on acrylic ester, a salt of a polymeric carboxylic acid, a sodium dioctyl sulphosuccinate, a stearate and Synperionic NTM wetting agent. These compounds are cheap, readily-available and of low toxicity.
- the binder is chosen from one or more of sucrose, dextrose, glucose, a water-soluble polymer based on acrylic acid, a water-soluble polymer based on acrylamide, a water-soluble polymer based on methacrylic acid, polyvinyl alcohol, a high molecular weight polyethylene glycol and a high molecular weight polypropylene glycol. These binders are cheap, readily-available and of low toxicity.
- the mixing is chosen from any one of ball milling, stirring or mechanical mixing with a beater. All of these methods are well-known and have proved to be successful.
- the homogenised mixture is preferably de-aerated prior to the forming of the mixture into the required shape. This reduces the incidence of undesirable voids occurring within the cast body. De-aeration is preferably by vacuum.
- Forming the mixture into the required shape preferably comprises the pouring of the homogenised mixture into a non-porous mould.
- the mould comprises a non-porous material inner surface.
- the non-porous material is a lining internally of the mould.
- Non-porous moulds are more readily reusable than porous moulds.
- Non-porous moulds are especially effective if the inner surface of the mould is treated with a mould release agent prior to pouring the mixture into the mould.
- the non-porous material is chosen from any one of polyurethane, silicone rubber, glass and polymethylmethacrylate. These materials are cheap, available and can be readily formed into moulds.
- forming the mixture into the required shape can comprise the pouring of the homogenised mixture into a porous mould.
- the drying process comprises drying at a temperature greater than ambient.
- the drying process can also comprise use of a desiccating substance.
- the boron carbide particles have a median particle size in the range 1.5 to 3.5 ⁇ m where at least 95% of the mass is less than 12.7 ⁇ m.
- the atomic ratio of boron to carbon is in the range 3.7:1 and 4.4:1.
- the boron carbide is more than 99.3% pure excluding boron oxide and boron nitride, or more than 97% pure including boron oxide and boron nitride.
- a method for preparing cast bodies according to the present invention starts with the mixing 1 of the binder system.
- 300g of commercially available boron carbide powder are mixed with 3g of Synperionic NTM in a mechanical mixer for 5 minutes with 40g of water. This forms the boron carbide slurry.
- the boron carbide powder typically has a specific surface area in the range 7-12m 2 /g.
- the Synperionic NTM acts as a dispersant, probably by coating the boron carbide particles such that the particles do not form undesirable large aggregates which fall out of suspension.
- a solution of 20g of an acrylic binder (Glascol HA4 available from Allied Colloids) in 40g of water is mixed with 9g of polyethylene glycol.
- the binder/polyethylene glycol mixture is then added to 40g of water.
- the molecular weight of the polyethylene glycol is about 200 (PEG 200), this being typical of a low molecular weight polymer used as a plasticiser.
- This binder/polyethylene glycol/water system is then mixed by a method well-known in the art and added to the boron carbide slurry. Mixing is then carried out for a further ten minutes.
- the resulting dispersant/plasticiser/boron carbide slurry is then decanted into a glass beaker and de-aerated 2 under vacuum until no gas bubbles are visible in the slurry.
- the slurry is then poured into a polyurethane mould 3 and allowed to dry 4 under ambient conditions.
- the cast body can be removed from the mould and is then suitable for sintering, for example as described in International Patent Application No. PCT/GB95/02029.
- the de-aeration process 2 minimises the incidence of undesirable voids which may form in the cast body. Such voids decrease strength and may cause loss of detail, since they will not be removed in any subsequent sintering process.
- the low molecular weight polyethylene glycol acts as a plasticiser which gives strength to the cast body. This decreases the likelihood of damaging the body prior to sintering.
- the polyurethane mould is non-porous and, hence, adhesion may occur between the mould and the cast body. Such adhesion may lead to damage of the cast body when it is removed from the mould. Coating of the internal surface of the mould with a mould release agent will improve performance when compared with the uncoated mould. Drying 4 takes place by evaporation of water from the slurry via open orifices present in the mould.
- the binder system is first prepared by adding 26g of sucrose to 60g of water and then mixing 1 in a mechanical mixer for 5 minutes: 300g of boron carbide powder having a surface area in the range 7-12m 2 /g, are then added to the sucrose solution and mixing is continued for another 10 minutes.
- This slurry is then decanted into a glass beaker and de-aerated 2 under vacuum until no bubbles are visible in, or on the surface of, the slurry.
- the de-aerated slurry is poured into a glass mould 3 lined with polymethylmethacrylate and allowed to dry under ambient conditions. After 3 hours, the mould is placed in an oven and the slurry/cast body is oven dried at 60°C for 2 hours. The cast body can then be removed from the mould and is suitable for sintering.
- sucrose acts as the binder system.
- the polymethylmethacrylate lining is an example of a non-porous mould lining. Oven drying accelerates the drying process 4 and helps to harden the cast body.
- Figure 2 shows an image of a sintered body (in this case, a Dutch domino) which was cast using a method in accordance with the present invention. This illustrates that the method in accordance with the present invention can give excellent reproduction of fine detail, with no undesirable voids being apparent.
- Figure 3 shows, on the left, an image of a cast body produced using a method in accordance with the present invention and, on the right, an image of a sintered body derived from an identical cast body to that shown on the left. This indicates that fine detail is reproduced both in the cast body and in the sintered body.
- the sizes of the two bodies indicate the degree of shrinkage that occurs on sintering.
- the manufacture of the dominoes is merely exemplary of the method in accordance with the present invention. Sintered boron carbide bodies manufactured using the method may be used, inter alia , for armour, machine parts and aeroengine components where the hardness of the material can be fully utilised.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Mechanical Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Ceramic Products (AREA)
- Producing Shaped Articles From Materials (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
Abstract
Description
Claims (20)
- A method of making a boron carbide cast body suitable for sintering including the successive steps of mixing boron carbide particles with an aqueous binder system to form a homogenised slurry mixture; casting the mixture into the required shape; and drying the mixture, wherein the boron carbide particles have a median particle size in the range 1.5 to 3.5µm.
- A method of making a boron carbide cast body according to Claim 1 wherein the specific area of the boron carbide particles is greater than 7 m2/g.
- A method of making a boron carbide cast body according to either of Claims 1 and 2, wherein the boron:carbon ratio is between 3.7:1 and 4.4:1.
- A method of making a boron carbide cast body according to any one preceding claim wherein the boron carbide is more than 99.3% pure excluding boron oxide or boron nitride, or more than 97% pure including boron oxide and boron nitride.
- A method of making a boron carbide cast body according to any one preceding claim wherein the binder system comprises a binder and a plasticiser.
- A method of making a boron carbide cast body according to Claim 5 wherein the plasticiser is chosen from one or more of glycerol, a low molecular weight polyethylene glycol and a low molecular weight polypropylene glycol.
- A method of making a boron carbide cast body according to any one of Claims 1 to 6 wherein the binder system includes a dispersant.
- A method of making a boron carbide cast body according to Claim 7 wherein the dispersant is one or more of a water-soluble copolymer based on acrylic ester, a salt of a polymeric carboxylic acid, a sodium dioctyl sulphosuccinate, a stearate and Synperionic N™ wetting agent.
- A method of making a boron carbide cast body according to any one of Claims 1 to 8 wherein the binder is chosen from one or more of sucrose, dextrose, glucose, polyvinyl alcohol, a water-soluble polymer based on acrylic acid, a water-soluble polymer based on acrylamide, a water-soluble polymer based on methacrylic acid, a high molecular weight polyethylene glycol and a high molecular weight polypropylene glycol.
- A method of making a boron carbide cast body according to any preceding Claim wherein the mixing is chosen from any one of ball milling, stirring or mechanical mixing with a beater.
- A method of making a boron carbide cast body according to any preceding Claim wherein the drying process comprises drying at a temperature greater than ambient.
- A method of making a boron carbide cast body according to any preceding Claim wherein the drying process comprises use of a desiccating substance.
- A method of making a boron carbide cast body according to any preceding Claim wherein forming the mixture into the required shape comprises the pouring of the homogenised mixture into a non-porous mould.
- A method of making a boron carbide cast body according to Claim 13 wherein the mould comprises a non-porous material inner surface.
- A method of making a boron carbide cast body according to Claim 14 wherein the non-porous material is a lining internally of the mould.
- A method of making a boron carbide cast body according to any one of Claims 13 to 15 wherein the non-porous material is chosen from any one of polyurethane, silicone rubber, glass and polymethylmethacrylate.
- A method of making a boron carbide cast body according to any one of Claims 1 to 12 wherein forming the mixture into the required shape comprises the pouring of the homogenised mixture into a porous mould.
- A method of making a boron carbide cast body according to any preceding Claim wherein the homogenised mixture is de-aerated prior to the forming of the mixture into the required shape.
- A method of making a boron carbide cast body according to Claim 18 wherein the homogenised mixture is de-aerated by vacuum.
- An article obtainable by a method in accordance with any one of Claims 1 to 19.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9910480A GB2349601A (en) | 1999-05-07 | 1999-05-07 | Boron carbide cast bodies |
GB9910480 | 1999-05-07 | ||
PCT/GB2000/001724 WO2000068165A1 (en) | 1999-05-07 | 2000-05-05 | Boron carbide cast bodies |
Publications (2)
Publication Number | Publication Date |
---|---|
EP1189852A1 EP1189852A1 (en) | 2002-03-27 |
EP1189852B1 true EP1189852B1 (en) | 2004-04-14 |
Family
ID=10852922
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP00927513A Expired - Lifetime EP1189852B1 (en) | 1999-05-07 | 2000-05-05 | Boron carbide cast bodies |
Country Status (11)
Country | Link |
---|---|
EP (1) | EP1189852B1 (en) |
JP (1) | JP4676066B2 (en) |
AT (1) | ATE264280T1 (en) |
AU (1) | AU4591000A (en) |
CA (1) | CA2373147C (en) |
DE (1) | DE60009903T2 (en) |
GB (1) | GB2349601A (en) |
MY (1) | MY122608A (en) |
TW (1) | TWI245752B (en) |
WO (1) | WO2000068165A1 (en) |
ZA (1) | ZA200109199B (en) |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2001072659A1 (en) | 2000-03-31 | 2001-10-04 | Toto Ltd. | Method for wet forming of powder, method for producing powder sintered compact, powdery sintered compact, and apparatus using powdery sintered compact |
US7592279B1 (en) | 2003-06-12 | 2009-09-22 | Georgia Tech Research Corporation | Boron carbide and boron carbide components |
US8377369B2 (en) | 2004-12-20 | 2013-02-19 | Georgia Tech Research Corporation | Density and hardness pressureless sintered and post-HIPed B4C |
CN101193663A (en) | 2005-04-11 | 2008-06-04 | 佐治亚技术研究公司 | Boron carbide component and methods for the manufacture thereof |
KR102574046B1 (en) * | 2018-06-13 | 2023-09-06 | 사반치 유니버시티 | Low-temperature production method of boron carbide |
CN110304923B (en) * | 2019-07-04 | 2021-11-23 | 东北大学 | Preparation method of boron carbide-based ceramic composite material based on particle grading |
CN112830798B (en) * | 2021-01-19 | 2022-05-06 | 哈尔滨工业大学 | Preparation method of boron carbide granulation powder for pressureless sintering |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1461509A (en) * | 1974-02-19 | 1977-01-13 | Battelle Institut E V | Processes for the production of catalyst carriers or catalysts systems having open pores |
DE2751998A1 (en) * | 1977-11-22 | 1979-05-23 | Kempten Elektroschmelz Gmbh | PROCESS FOR MANUFACTURING POLYCRYSTALLINE DENSE MOLDED BODIES FROM BORON CARBIDE BY PRESSURELESS SINTERING |
GB2014193B (en) * | 1978-02-13 | 1982-06-30 | Atomic Energy Authority Uk | Sintered boron carbide containing free carbon |
JPS60118673A (en) * | 1983-11-30 | 1985-06-26 | 電気化学工業株式会社 | Manufacture of boron carbide formed body |
US4978643A (en) * | 1987-04-09 | 1990-12-18 | Ceramics Process Systems Corporation | Forming whisker reinforced sintered ceramics with polymerizable binder precursors |
DE3917734A1 (en) * | 1989-05-31 | 1990-12-06 | Hoechst Ag | METHOD FOR PRODUCING CERAMIC MOLDED BODIES BY FREEZING AQUEOUS SLICKER |
JPH0812434A (en) * | 1993-11-01 | 1996-01-16 | Noritake Co Ltd | Production of sintered b4c material and sintered b4c compact |
GB9418817D0 (en) * | 1994-09-19 | 1994-11-09 | Secr Defence | Sintered boron carbide articles |
JPH0957719A (en) * | 1995-08-22 | 1997-03-04 | Mitsubishi Materials Corp | Method for casting of molding with spiral groove |
JP3571540B2 (en) * | 1998-02-04 | 2004-09-29 | 三井金属鉱業株式会社 | Filtration mold and method for producing ceramic sintered body using the mold |
-
1999
- 1999-05-07 GB GB9910480A patent/GB2349601A/en not_active Withdrawn
-
2000
- 2000-05-05 DE DE60009903T patent/DE60009903T2/en not_active Expired - Lifetime
- 2000-05-05 CA CA2373147A patent/CA2373147C/en not_active Expired - Fee Related
- 2000-05-05 EP EP00927513A patent/EP1189852B1/en not_active Expired - Lifetime
- 2000-05-05 WO PCT/GB2000/001724 patent/WO2000068165A1/en active Search and Examination
- 2000-05-05 AU AU45910/00A patent/AU4591000A/en not_active Abandoned
- 2000-05-05 AT AT00927513T patent/ATE264280T1/en not_active IP Right Cessation
- 2000-05-05 JP JP2000617147A patent/JP4676066B2/en not_active Expired - Fee Related
- 2000-05-05 MY MYPI20001951A patent/MY122608A/en unknown
- 2000-05-29 TW TW089110362A patent/TWI245752B/en not_active IP Right Cessation
-
2001
- 2001-11-07 ZA ZA200109199A patent/ZA200109199B/en unknown
Also Published As
Publication number | Publication date |
---|---|
DE60009903T2 (en) | 2005-03-17 |
EP1189852A1 (en) | 2002-03-27 |
MY122608A (en) | 2006-04-29 |
ATE264280T1 (en) | 2004-04-15 |
CA2373147C (en) | 2010-11-16 |
GB9910480D0 (en) | 1999-07-07 |
JP4676066B2 (en) | 2011-04-27 |
CA2373147A1 (en) | 2000-11-16 |
AU4591000A (en) | 2000-11-21 |
GB2349601A (en) | 2000-11-08 |
ZA200109199B (en) | 2003-04-30 |
TWI245752B (en) | 2005-12-21 |
WO2000068165A1 (en) | 2000-11-16 |
DE60009903D1 (en) | 2004-05-19 |
JP2002544014A (en) | 2002-12-24 |
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